Production includes crop and animal yield and their
quality. Numerous individual studies have compared yield differences
between organic and conventional systems. These data have
been synthesized in several meta-analyses or reviews; according
to these studies, yield averages are 8 to 25% lower in organic
systems. However, with certain crops, growing conditions and
management practices, organic systems come closer to matching
conventional systems in terms of yields. According to one such
synthesis study, the best yielding organically grown crops or crop
groups are rice, soybeans, corn and grass-clover, which yield 6 to
11% less than conventional systems; the lowest yielding are fruits and wheat, which yield 28 and 27% less, respectively. Another
meta-analysis found fruits, soybeans and oil seed to be the highest
yielding organic crops, and wheat and vegetables the lowest, yielding
37 and 33% less than conventional systems respectively. In
cases where organic crop rotations depend on green manure crops,
food production over the whole rotation may be lower than one-toone
crop yield comparisons suggest.